'Declaration Public Enum CompressionMethod Inherits System.Enum Implements System.IComparable, System.IConvertible, System.IFormattable
'Usage Dim instance As CompressionMethod
public enum CompressionMethod : System.Enum, System.IComparable, System.IConvertible, System.IFormattable
| Member | Value | Description |
|---|---|---|
| BWT | 18 | The raw BWT block-sorting algorithm. Produces smaller compressed output than the BZip2 method, but is not compatible with WinZip. It is compatible with zip files created using the BWT compression method offered by Xceed Zip Compression Library ActiveX. |
| BZip2 | 12 | A BWT-based block-sorting algorithm used in zip files created with WinZip 11.0 and up. An excellent alternative to Deflate and Deflate64 when speed can be traded off. |
| Deflated | 8 | Deflate algorithm. Standard algorithm used by the PKZip 2.04g format. |
| Deflated64 | 9 | Also know as Enhanced Deflate. Deflate64 is a variation of the Deflate algorithm that uses a 64K sliding window rather than a 32K window in order to compress a sequence of bits. Deflate64 takes longer to compress data than Deflate, however it provides better compression. The Xceed Self-Extractor Module does not support the Deflated64 compression method. |
| LZMA | 14 | The Lempel-Ziv-Markov chain-Algorithm (LZMA) uses an improved and optimized version of the Lempel-Ziv (LZ77) compression algorithm, backed by a Markov chain range encoder. It uses a variable dictionary size. Used in zip files created with WinZip 12.0 and up. LZMA typically provides much better compression than the Deflate and Deflate64 algorithms at the expense of speed and memory usage when compressing. It also typically provides compression ratios a little better than BZip2/BWT and PPMd while being a little faster. Compression usually requires (<dictionary size> * 11.5 + 6 MB) |
| PPMd | 98 | A PPM-based predictor algorithm used in zip files created with Winzip 11.0 and up. In our tests, especially with text files and XML files, the PPMd method generally produced the smallest compressed output. Xceed recommends that the PPMd compression method be selected when dealing with text files, XML files, and other files with high redundancy, as this is where the PPMd algorithm is able to create smaller files than the other compression methods. |
| Stored | 0 | No compression is applied. |
The PPMd algorithm uses a custom memory management system called SubAllocator. In a zip file, the memory size the SubAllocator uses is defined in the WinZip PPMd header for the compressed file and this header's value is used when decompressing the data. In general, WinZip uses 64Mb. Since the algorithm used was not optimized from the original PPMd version I revision 1, the SubAllocator initially requires the total amount of memory specified in the PPMd compressor. This means you must have at least 64 MB free of RAM when using this compression method.
The compression level only applies to the Deflated, Deflated64, PPMd, and LZMA compression methods. It does not apply to the BZip2 or BWT compression methods.
System.Object
System.ValueType
System.Enum
Xceed.Compression.CompressionMethod
Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2